Arrows conventionally include fletchings mounted on their rear ends to provide flight stability. Usually three and sometimes four fletchings are mounted in a circumferentially spaced relationship about the rear end of the arrow shaft. In addition, two fletchings and a single fletching have also been utilized on arrow shafts in the past but have never received any significant commercial acceptance by archers.
Feathers were the only type of fletchings conventionally utilized by archers until about five years or so ago when "rubber" fletchings gained acceptance. Actually, the designation "rubber" fletching is now somewhat of a misnomer since this type of fletching is presently made from synthetic plastic, although such plastic does have some rubber-like characteristics. Usually rubber fletchings are extruded with a mounting foot and a vane projecting from the foot, and the fletching is cut after the extrusion to the required length with the vane having the desired shape. In addition to feather and rubber fletchings, sheet plastic has also been previously utilized to make fletchings but has never received any significant commercial acceptance by archers.
Arrow spin or rotation is desirable to maintain flight stability and is usually achieved by mounting fletchings on the arrow shaft either at a slight angle with respect to the elongated axis thereof or in a helical configuration thereabout such that a screw action takes place during forward flight through the air. The consequent rotation stabilizes the arrow flight even when subjected to head, side, and tail winds that would otherwise significantly alter the flight trajectory. Such arrow rotation is particularly important with hunting arrows whose flat blade type points can tend to "sail" if there is not sufficient stabilizing rotation.
Prior art arrow fletchings of the type described above are illustrated by U.S. Pat. Nos.: 2,193,397; 2,277,743; 2,525,332, 3,106,400; 3,539,187; 3,595,579; 3,749,403; 3,895,802; 4,003,576; and 4,088,323.
My prior U.S. Pat. Nos. 3,756,602 and 4,012,043 disclose arrow fletchings made by sharply bending sheet plastic to the desired shape. The arrow fletching disclosed by my U.S. Pat. No. 3,756,602 includes vanes that are spaced outwardly from the shaft an increasing extent in the forward direction so as to provide a construction that compensates for cross-winds by steering the arrow into the wind. The arrow fletching disclosed by my U.S. Pat. No. 4,012,043 includes vanes that each define a pocket of decreasing volume from front to rear to effect a pressure buildup that causes stabilizing rotation of the arrow during flight.
Frictional drag generated by arrow fletchings during flight is affected by wind changes and thus alters the flight trajectory. Wind changes are a much greater problem with the longer distances involved in target shooting as compared to hunting, since any change in the frictional drag due to wind changes is effective over a greater period of time with the higher trajectory required for longer distances. Also, arrow fletchings heretofore have not had a construction capable of compensating for wind changes in order to maintain the desired flight trajectory.